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Evidence at last that the proton has intrinsic charm

An analysis of the distribution of the elementary particles that make up the proton provides evidence that it contains a type of quark known as an intrinsic charm quark — verifying a proposal made four decades ago.
  1. Ramona Vogt

    1. Ramona Vogt is at Lawrence Livermore National Laboratory, Livermore, California 94550, USA, and in the Department of Physics and Astronomy, University of California, Davis, Davis, California, USA.

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Physics textbooks describe the proton as a subatomic particle that contains three quarks, bound together by elementary particles known as gluons. But quantum theory predicts that the proton can contain other quark–antiquark pairs, including some quarks — known as charm quarks — that are more massive than the proton itself. These charm quarks are thought to be ‘intrinsic’, meaning that they are part of the proton over long timescales and not produced by interactions with a particle that is external to the proton1,2. However, attempts to confirm intrinsic charm in experiments have so far fallen short. In a paper in Nature, the NNPDF Collaboration3 reports an analysis of collision data that acts as evidence — if not the discovery — of intrinsic charm in the proton.

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Nature 608, 477-479 (2022)

doi: https://doi.org/10.1038/d41586-022-02186-w

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Competing Interests

The author declares no competing interests.

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